In 2019 CBR (Comic Book Resources) rated this season as the second best of all Star Trek seasons up until that time. This placed it just behind Deep Space 9 Season 6. https://www.cbr.com/every-star-trek-tv-season-ranked/

Amok Time (September 15, 1967)

Who Mourns For Adonais? (September 22, 1967)

The Changeling (September 29, 1967)

Mirror, Mirror (October 6, 1967)

The Apple (October 13, 1967)

The Doomsday Machine (October 20, 1967)

Catspaw (October 27, 1967)

I, Mudd (November 3, 1967)

Metamorphosis (November 10, 1967)

Journey to Babel (November 17, 1967)

Friday’s Child (December 1, 1967)

The Deadly Years (December 8, 1967)

Obsession (December 15, 1967)

Wolf in the Fold (December 22, 1967)

The Trouble with Tribbles (December 29, 1967)

The Gamesters of Triskelion (January 5, 1968)

A Piece of the Action (January 12, 1968)

The Immunity Syndrome (January 19, 1968)

A Private Little War (February 2, 1968)

Return to Tomorrow (February 9, 1968)

Patterns of Force (February 16, 1968)

By Any Other Name (February 23, 1968)

The Omega Glory (March 1, 1968)

The Ultimate Computer (March 8, 1968)

Bread and Circuses (March 15,1968)

Assignment: Earth (March 22, 1968)